JP2003138166A - Water-based primer and method for bonding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-based primer providing a bond strength equal to that of a conventional e primer. SOLUTION: This water-based primer is obtained by using a polychloroprene and sodium silicate as an essential component, and dispersing or dissolving them in water. Especially, the sodium silicate is sodium orthosilicate. The method for bonding comprises bonding an adherend by using the water-based primer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention obtains sufficient adhesive strength when adhering adherends such as rubber, elastomer and synthetic resin, especially when using a polychloroprene-based water-based adhesive. Therefore, it is a novel water-based primer to be applied on the surface of the adherend in advance before applying the adhesive.

[0002]

2. Description of the Related Art Conventionally, as a method for adhering a hard-to-adhere adherend such as rubber, elastomer, and synthetic resin, a solvent-type adhesive such as polychloroprene is applied after applying a solvent-type primer on the surface of the adherend. The bonding method used was mainly adopted. However, the solvent-based adhesives are toluene, ethyl acetate,
Since a large amount of organic solvent such as methyl ethyl ketone is used, it is not preferable in terms of worker safety and health and environment. Therefore, the demand for water-based adhesives and primers has been increasing year by year. Regarding the water-based adhesive, for example, JP 2001-64616 A and JP 2001-A
Several proposals have been made, such as 26756. But,
Nothing is known about a primer that can be put to practical use, and in practice, for example, JP-A-2001-164176 is used.
The present situation is that a solvent-type primer as shown in (4) is used.

[0003]

SUMMARY OF THE INVENTION In view of the above situation, it is an object of the present invention to provide an aqueous primer which gives an adhesive strength comparable to that of a conventional solvent type primer.

[0004]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that polychloroprene and sodium silicate are essential components, and they are dispersed or dissolved in water. It was found that the product gives excellent adhesive strength as a water-based primer, and completed the present invention.

That is, the present invention is a water-based primer characterized in that polychloroprene and sodium silicate are essential components, and these are dispersed or dissolved in water, and sodium orthosilicate is particularly used as sodium silicate. It was a water-based primer. Further, it is an adhesion method of adhering an adherend using these water-based primers.

The details of the present invention will be described below. The polychloroprene referred to in the present invention means 2-chloro-1,3
A butadiene (hereinafter referred to as “chloroprene”) homopolymer or a copolymer of chloroprene and a monomer copolymerizable with chloroprene. The term "copolymer" as used herein also includes a graft copolymer obtained by graft-polymerizing another monomer in the presence of polychloroprene.

Examples of the monomer copolymerizable with chloroprene include 2,3-dichloro-1,3-butadiene,
Examples thereof include 1-chloro-1,3-butadiene, butadiene, isoprene, styrene, acrylonitrile, acrylic acid and its esters, methacrylic acid and its esters, and two or more kinds may be used as necessary.

The method for polymerizing polychloroprene is not particularly limited, but the method by emulsion polymerization is general and simple. In order to complete the present invention, it is necessary to disperse polychloroprene in water,
In the case of emulsion polymerization, the obtained polychloroprene latex can be used as it is.

The emulsifier and / or dispersant used in the emulsion polymerization of the polychloroprene latex is not particularly limited, and various anionic type, nonionic type and cation type that are usually used in chloroprene latex can be used. Anionic emulsifiers include carboxylic acid type,
Examples thereof include sulfonic acid type and sulfuric acid ester type, and examples thereof include alkali metal salts of rosin acid, alkyl sulfonates having 8 to 20 carbon atoms, alkylaryl sulfates, condensates of sodium naphthalenesulfonate and formaldehyde, and the like. Specific examples of the nonionic type include polyvinyl alcohol or its copolymer (for example, copolymer with acrylamide), polyvinyl ether or its copolymer (for example, copolymer with maleic acid), polyvinylpyrrolidone or its copolymer. Examples thereof include polymers (for example, copolymers with vinyl acetate), those obtained by chemically modifying these (co) polymers, and cellulose derivatives (hydroxyethyl cellulose).
Specific examples of the cation type include an aliphatic amine salt and an aliphatic quaternary ammonium salt. Examples thereof include octadecyltrimethylammonium chloride, dodecyltrimethylammonium chloride and dilauryldimethylammonium chloride. However, the polychloroprene latex used for the primer of the present invention preferably contains rosin acid and / or an alkali metal rosin acid salt.

The addition amount of the emulsifier and / or dispersant in the polychloroprene latex of the present invention is preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the total amount of the initially charged monomers. If it is less than 0.5 parts by mass, the emulsifying power is not sufficient, and if it exceeds 20 parts by mass, there is a drawback that the water-resistant adhesive strength is lowered.

The polymerization temperature of the polychloroprene latex in the present invention is not particularly limited, but in order to smoothly carry out the polymerization reaction, the polymerization temperature is preferably 0 to 50 ° C. As a polymerization initiator, a persulfate such as potassium persulfate, an organic peroxide such as tert-butyl hydroperoxide, or the like is preferably used, but it is not limited thereto.

The type of chain transfer agent used for the polymerization is not particularly limited, and those usually used for emulsion polymerization of chloroprene can be used. For example, long-chain alkyl mercaptans such as n-dodecyl mercaptan and tert-dodecyl mercaptan, dialkylxanthogen disulfides such as diisopropylxanthogen disulfide and diethylxanthogen disulfide, and known chain transfer agents such as iodoform can be used.

The polychloroprene polymerization terminator (polymerization inhibitor) is not particularly limited and, for example, 2,6-tert-butyl-4-methylphenol, phenothiazine, hydroxyamine and the like can be used.

The final polymerization rate of polychloroprene is not particularly limited and can be arbitrarily adjusted, and unreacted monomers are removed by the demomer operation.
The method is not particularly limited. The solid content concentration of the polychloroprene latex of the present invention can be controlled to a required concentration by concentrating or diluting it by adding water or the like. The concentration method includes concentration under reduced pressure, but is not particularly limited.

The structure of the polychloroprene latex in the present invention is not particularly limited, but the polymerization temperature, polymerization initiator, chain transfer agent, polymerization terminator, final polymerization rate, demonomer, concentration conditions, etc. are suitable. It is possible to adjust the solid content concentration, the molecular weight of the toluene soluble portion, the toluene insoluble content (gel content) and the like by selecting and controlling the above.
From the viewpoint of adhesive properties, it is preferable to adjust the gel content of the (co) polymer in the polychloroprene latex to 3 to 60 mass% from the viewpoint of the balance between the initial adhesive strength and the normal adhesive strength.

Sodium silicate has the general formula Na ₂ O.nS
represented by iO ₂ · mH ₂ O, the molar ratio of Na ₂ O and SiO ₂ ,
That is, it is divided into sodium orthosilicate, sodium metasilicate, sodium silicate No. 1, sodium silicate No. 2, sodium silicate No. 3, sodium silicate No. 4, etc. according to the coefficient n. The polychloroprene latex composition of the present invention Any type can be used for. However, from the viewpoint of adhesive strength, it is more preferable to use sodium orthosilicate. The amount of sodium silicate added is not particularly specified, but from the viewpoint of adhesive strength, 0.1 to 30 parts by weight is preferable per 100 parts by weight of polychloroprene (solid content), and more preferably 0.5. 10 to 10 parts by weight. The method of adding sodium silicate is not particularly limited, but it can be used by directly dissolving it in a polychloroprene latex other than sodium metasilicate, or by dissolving it in water and then adding it to the polychloroprene latex. Is also possible. In the case of sodium metasilicate, it can be directly added to the polychloroprene-based latex, but more preferably, it is once emulsified and dispersed in water using a suitable emulsifier, and then the emulsion is added to the polychloroprene-based latex. Is used.

The solid content concentration of the primer of the present invention is not particularly limited, but is preferably 60% by weight or less,
More preferably, it is 10 to 30% by weight. 60% by weight
When the solid content is set to the above range, the problem of impairing the stability of the emulsification system is likely to occur, which is a practical problem. Also, 10% by weight
In the case of a low solid content concentration of less than 30% by weight or in the case of a solid content concentration of more than 30% by weight, it becomes difficult to control the thickness of the primer layer after drying to an optimum range. The concentration is practically preferable.

The primer of the present invention contains polychloroprene and sodium silicate as essential components and exhibits sufficient effects even if they are dispersed or dissolved in water. However, initial adhesive strength, water resistant adhesive strength, and stickiness retention In order to make properties such as time more practical, it is effective to add a tackifying resin.

When a tackifying resin is mixed with an aqueous adhesive
However, the type is not particularly limited. Specifically
Is rosin resin, polymerized rosin resin, α-pinene resin, β
-Pinene resin, terpene phenol resin, C_FiveFractional stone
Oil resin, C₉Fraction petroleum resin, C _Five/ C₉Fractionated petroleum tree
Oil, DCPD petroleum resin, alkylphenol resin, ki
Siren resin, coumarone resin, coumarone indene resin, etc.
Is mentioned. Softening to get sufficient initial adhesion
A resin having a point temperature of 50 to 160 ° C. is preferable.

The method of adding the tackifying resin is not particularly limited, but it is preferable to add it as an aqueous emulsion in order to uniformly disperse the resin in the primer. Further, a method for producing an aqueous emulsion of a tackifying resin includes a method of emulsifying / dispersing a substance dissolved in an organic solvent such as toluene in water using an emulsifier, and then removing the organic solvent by heating under reduced pressure and removing fine particles. Although there is a method of pulverizing into 1 to emulsify / disperse, etc., the former method is preferable because an emulsion of finer particles can be prepared.

In addition to the above-mentioned substances, the primer in the present invention has a thickening agent, a metal oxide, a filler, a film-forming aid, an ultraviolet absorber, an antioxidant, a plasticizer, and
A vulcanizing agent, a vulcanization accelerator, an antifoaming agent and the like can be optionally added.

By adding a thickener to the primer, it is possible to adjust the viscosity to an arbitrary value. Specific thickeners include polyvinyl alcohol (PVA), sodium polyacrylate, water-soluble polyurethane, associative polyurethane emulsion, alkali swelling acrylic emulsion, carboxymethyl cellulose (CMC), methyl cellulose (MC), hydroxyethyl cellulose. (HEC), hydroxypropyl cellulose (HP
C), polyvinyl alcohol, synthetic smectite and the like. A suitable amount of the thickening agent is 0.01% based on 100 parts by mass of the solid content of the polychloroprene latex.
10 to 10 parts by mass (converted to solid content). This is because if it is compounded within this range, the repelling of the primer on the surface of the elastomer material can be prevented.

The viscosity of the primer may be adjusted according to the coating method and the specifications of the coating apparatus, but it is 10 to 1500.
0 [mPa · s] (B type viscometer, 25 ° C, 30 rpm)
Is preferred. If the viscosity is less than 10 [mPa · s], repulsion on the surface of the elastomer material may become a problem,
When the viscosity is higher than 15000 [mPa · s], uniform coating may be difficult in some cases.

The coating method and coating apparatus specifications required for coating the primer of the present invention are not particularly limited. As a specific example, a spray method, a curtain flow coater method, a bar coater method, a roll coater method or the like can be applied. Further, the roll coater method includes a gravure roll coater method and a reverse gravure roll coater method. However, when the application area is small, a method of applying with a brush or a brush, or more preferably, a method of soaking in a sponge or cloth and then gently wiping the surface of the elastomer material is preferable. The coating amount is not particularly limited, but it is preferable that the thickness of the primer layer is thinner than the thickness of the adhesive layer, because a stronger adhesive structure can be obtained. Specifically, 5 to 100 g / m ² (wet) is preferable.

The primer of the present invention can be applied to any type of adhesive such as polyurethane type, acrylic type, vinyl acetate, etc. regardless of solvent type or water type, but to polychloroprene type adhesive. It is particularly preferably used regardless of solvent type or water type.

The material to which the primer of the present invention is applied, such as rubber, elastomer and synthetic resin, is not particularly limited, but specifically, butadiene rubber (BR),
Chloroprene rubber (CR), natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SB
R), butyl rubber (IIR), norbornene rubber (NO
R), nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), brominated butyl rubber (BIIR), chlorinated butyl rubber (CIIR), acrylonitrile-isoprene copolymer (NIR), ethylene-propylene-diene rubber (EPDM), Such as vulcanized rubber, styrene-butadiene-styrene / block copolymer (SBS), polyester-based, urethane-based, olefin-based thermoplastic elastomer, vinyl chloride resin (PVC), ethylene-vinyl acetate copolymer (EVA) ), 1,2-polybutadiene (RB),
Examples include polyolefin resins, styrene resins, acrylonitrile-butadiene-styrene copolymers (ABS) and the like. Further, the compounding composition, cross-linking density, shape and the like of these materials are not particularly limited, and a foam can be applied. It can be preferably used in any field such as grips of sports equipment, shoe soles, building materials, etc.

[0027]

EXAMPLES The effects of the present invention will be described in detail below with reference to examples and comparative examples, but these examples do not limit the present invention. In the following description, parts and% are based on mass unless otherwise specified.

[Experimental Example 1] Using a reactor having an internal volume of 3 liters, under a nitrogen stream, 100 parts of water and 5 parts of disproportionated rosin acid.
Parts, sodium hydroxide 0.6 parts, potassium hydroxide 0.7
Parts, 0.3 parts of sodium salt of formaldehyde naphthalene sulfonic acid condensate, and 0.3 parts of sodium bisulfite were charged, and after dissolution, chloroprene monomer 1 was stirred.
00 parts and 0.14 parts of n-dodecyl mercaptan were added. Polymerization was carried out at 10 ° C. in a nitrogen atmosphere using potassium persulfate as an initiator, and when the polymerization rate reached 90%, an emulsion of phenothiazine was added to terminate the polymerization. Unreacted monomers were removed under reduced pressure to obtain polychloroprene latex. Further, the water content was evaporated under reduced pressure for concentration to adjust the solid content to 60% by mass.

[Experimental Example 2] Using a reactor having an internal volume of 3 liters, under a nitrogen stream, 120 parts of water, and disproportionated rosin acid 4
Parts, sodium hydroxide 0.8 parts, sodium salt of formaldehyde naphthalene sulfonic acid condensate 0.5 parts, and sodium bisulfite 0.3 parts are charged, and after dissolution, 100 parts of chloroprene monomer and n- are added with stirring. 0.25 parts of dodecyl mercaptan was added. Polymerization was carried out at 10 ° C. in a nitrogen atmosphere using potassium persulfate as an initiator, and when the polymerization rate reached 70%, an emulsion of phenothiazine was added to terminate the polymerization. After removing the unreacted monomer under reduced pressure, polychloroprene chips were obtained by a conventional freeze-coagulation drying method.

[Example 1] Using the polychloroprene latex obtained in Experimental Example 1, a solid content concentration of 53 was added as a tackifying resin to 100 parts of the polychloroprene latex.
% Terpene phenolic resin emulsion (Tamanor E
-100 / Arakawa Chemical Co., Ltd.) and 50 parts of sodium silicate No. 1 (manufactured by Asahi Denka Co., Ltd.) were added. Further, pure water was added to adjust the solid content of the entire formulation to 20% to prepare a primer.

Further, to 100 parts of the polychloroprene latex obtained in Experimental Example 1, 5 parts of a terpene phenol resin emulsion (Tamanor E-100 / Arakawa Chemical Industry Co., Ltd.) having a solid content concentration of 53% was used as a tackifying resin.
0 part, 2.0 parts of sodium polyacrylate aqueous solution-based thickener (Aron A-20L / manufactured by Toagosei Co., Ltd.), aluminum hydroxide powder (Hijilite H-4) as a filler.
2M / manufactured by Showa Denko K.K.), 2 parts of a zinc oxide dispersion having a solid content of 50% as an acid acceptor, and a water-dispersible isocyanate compound (Takenate WD-73) as a curing agent.
0 / manufactured by Mitsui Takeda Chemical Co., Ltd.) in 2 parts to prepare a chloroprene water-based adhesive.

Vulcanized styrene butadiene rubber (sulfurized SBR, size of adhesive margin part is 20 mm in width) after buffing (adhering surface) of the adhesive surface and removing shavings by washing with acetone
The surface of each of the two sheets (× length 70 mm) was lightly wiped with a gauze soaked with a primer, and dried in an atmosphere of 60 ° C. for 10 minutes. An adhesive of 200 g (wet) / m ² was applied thereon with a brush, dried for 6 minutes in an atmosphere of 60 ° C., then laminated and pressure-bonded with a hand roller. The test pieces obtained by this method were evaluated as follows.
[Initial Adhesive Strength Evaluation Test] Ten minutes after pressure bonding, T-type peel strength was measured with a tensile tester at a tensile speed of 200 mm / min. [Normal-state adhesive strength evaluation test] One day after pressure bonding, the T-type peel strength was measured with a tensile tester at a tensile speed of 200 mm / min.

Examples 2 to 4 Tests were conducted in the same manner as in Example 1 except that the type of sodium silicate was changed as shown in Table 1.

Example 5 A test was conducted in the same manner as in Example 1 except that the terpene phenolic resin emulsion was not added.

Example 6 100 g of the chips of polychloroprene obtained in Experimental Example 2 were placed in a reactor having an internal volume of 1 liter, and 600 g of toluene was added and dissolved with stirring.
After the dissolution, 50 g of methyl methacrylate was added, and benzoyl peroxide was used as an initiator to carry out graft polymerization at 85 ° C. for 5 hours. A solution obtained by adding 2 parts of polyisocyanate (manufactured by Dismodur RFE / Bayer) to this chloroprene-graft copolymer solution was used as a solvent-based adhesive and used in Example 6.

[Comparative Example 1] An adhesion test was carried out by using only the water-based adhesive prepared in Example 1 without using a primer.

[Comparative Example 2] A test was carried out in the same manner as in Example 1 except that a primer was prepared without adding sodium silicate and subjected to the test.

[Comparative Example 3] The chloroprene-graft copolymer solution obtained in Example 7 was diluted with toluene and adjusted to a solid content concentration of 5% to prepare a solvent-type primer.

The test results obtained are summarized in Table 1.

[0040]

[Table 1]

[0041]

As is clear from Table 1, the primers (Examples 1 to 6) of the present invention exhibit adhesive strengths equal to or higher than those of the conventional solvent-based primer, and are suitable for water-based adhesives and solvent-based adhesives. Regardless, it shows high adhesive strength.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09J 5/02 C09J 5/02 F term (reference) 4F006 AA04 AA12 AA13 AA14 AA15 AA17 AA35 AA58 AB05 AB76 BA01 EA04 4J038 BA232 CA081 CR012 HA456 KA08 MA08 MA10 NA12 4J040 CA141 JA03 MA10 MA12 PA09

Claims (5)

[Claims] 1. A water-based primer comprising polychloroprene and sodium silicate as essential components, which are dispersed or dissolved in water. 2. The primer according to claim 1, wherein the sodium silicate is sodium orthosilicate. 3. The water-based primer according to claim 1 or 2, wherein the solid content is adjusted to a range of 10 to 30% by weight. 4. The water-based primer according to claim 1, further comprising a tackifying resin emulsion. 5. A bonding method for bonding an adherend using the water-based primer according to any one of claims 1 to 4.